The invention relates to an operational amplifier comprising at least a first amplifier stage, a second amplifier stage driven by the first amplifier stage, and a first and a second junction point, a first capacitive signal path for improving the high-frequency properties of the operational amplifier being arrangeable or arranged between said junction points, which first junction point is coupled to an output of the first amplifier stage and which second junction point is coupled to an output of the second amplifier stage, the gain from the first junction point to the second junction being noninverting and the impedance of the output of the second amplifier being high relative to the impedance of the first juntion point.
Such an operational amplifier is known from U.S. patent application Ser. No. 252,483, filed Apr. 8, 1981, and now U.S. Pat. No. 4,405,900 which is herewith incorporated by reference. This known operational amplifier comprises a voltage amplifier having a low-impedance output (the first amplifier stage) followed by a transconductance amplifier (the second amplifier stage) across which a high-frequency feed-forward path (the first capactive signal path) is arranged. This enables frequency compensation to be applied to the operational amplifier in order to obtain a 6 dB/octave roll-off without a loss of bandwidth because the 0-dB bandwidth of the operational amplifier is equal to the 0-dB bandwidth of the first amplifier stage as a result of this compensation. In addition, this known operational amplifier has the advantage that via said capacitive signal path, the high-impedance output of the second amplifier stage is loaded by the low-impedance output of the first stage for high frequencies, so that the high-frequency noise of this operational amplifier is reduced.